Generally, a semiconductor manufacturing process includes a fabrication process and an assembly process. The fabrication process means a process of manufacturing semiconductor chips by depositing thin films on a wafer in various process chambers and selectively etching the deposited films in a repeated way to form a predetermined pattern. The assembly process means a process of individually separating the chips manufactured in the fabrication process and then coupling the individual chip to a lead frame to assemble a final product.
At this time, the process of depositing thin films on a wafer or etching the films deposited on the wafer is performed at high temperature by using harmful gases such as silane, arsine, and boron chloride and process gases such as hydrogen in a process chamber. While such a process is performed, a large amount of various pyrophoric gases and byproduct gas containing harmful components and corrosive impurities are generated in the process chamber.
Thus, a semiconductor manufacturing apparatus is provided with a scrubber, which purifies byproduct gas discharged from a process chamber and discharges the purified byproduct gas to the atmosphere, at a downstream side of a vacuum pump for making the process chamber into a vacuous state.
However, while flowing from the process chamber to the vacuum pump and the scrubber via pipes 15a and 15b respectively, the harmful byproduct gas generated from the process chamber is easily solidified and accumulated, thereby resulting in blockage.
Thus, in order to solve the blockage problem caused by the solidification of byproduct gas, a nitrogen gas injection device 12 for injecting a high temperature nitrogen gas into a pipe in which a byproduct gas flows, particularly a pipe of a discharge side of a vacuum pump has been developed as disclosed in Korean Laid-open Patent Publication No. 2005-88649.
However, the conventional nitrogen gas injection device 12 which is provided as an external type had a limitation in that a blockage problem in a silencer 4 installed inside the vacuum pump is not solved. The silencer 4 is installed to suppress noise in the vacuum pump. However, since the silencer 4 is connected to a discharging portion 3 of a pump section 2 for performing pumping operation and thus positioned at a point which a large amount of byproducts pass through at once, the silencer 4 is always exposed to the blockage problem caused by the byproduct, but there is no obvious solution.